Gas-adsorbing elements, their method of manufacture, and devices incorporating such adsorbent elements

ABSTRACT

A gas-adsorbing element associated with a thermal source which is successively a cold source and then a hot source, and so on. The gas-adsorbent element is constituted by a ductile metallic support having an extended surface and, on at least one surface of said support, a coating of a gas-adsorbing product such as zeolite, constituted by material in the form of particles incrusted by compression between each other and on the support of ductile metal. This adsorbent element is prepared, for example by passing an aluminum tape between two cylinders of a rolling mill on which particles of the adsorbent product are deposited by hoppers. An adsorbent element of this kind can be incorporated in a vacuum pump, in a purification device, a compressor or a refrigerator.

O United States Patent [151 3,638,403 Delacour et al. Feb. 1, 1972 [54] GAS-ADSORBING ELEMENTS, THEIR References Cited METHOD OF MANUFACTURE, AND

UNITED STATES PATENTS DEVICES INCORPORATING SUCH 2 7 738 3/ 959 H k l 1 AD BENT ELEMENT cc ..l 17 3 80R S 3,296,773 1/1967 Hemstreet ..55/389 [72] Inventors: Pierre Delaeour, Noyarey; Pierre Lan- 3,303,634 2/1967 Berrian ..55/35 glade; Michel Renard, both of Grenoble, 3,309,844 3/1967 Hemstreet et al "55/75 all of France Primary Examiner-Charles N. Hart [73] Assrgnee: L Arr Lrqurde, Socrete Anonyme pour letude et lexploitation des procedes Attorney-Young & Thompson [57 1 ABSTRACT [22] Filed: 1969 A gas-adsorbing element associated with a thermal source [2]] Appl. No.: 837,517 which is successively a cold source and then a hot source, and so on. The gas-adsorbent element is constituted by a ductile metallic support having an extended surface and, on at least [30] Fomgn Appummn Pmmy Data one surface of said support, a coating of a gas-adsorbing July 5, 1968- France 1 58! 1 1 product such as zeolite, constituted y material in the form of particles incrusted by compression between each other and on [52] U.S.Cl ..55/389, 1l7/3l the pp r f uctile m l- This adsorbent element is [51] int. Cl. ..-.B0ld 53/04, BOSb 7/14 pr pared, for example by passing an aluminum tape between [58] Field of Search ..55/74, 75, 387, 389, 27; w yli f a r lling mill on which particles of the adsor- 1 17/21, 31 bent product are deposited by hoppers. An adsorbent element of this kind can be incorporated in a vacuum pump, in a purification device, a compressor or a refrigerator.

24 Claims, 12 Drawing Figures ing gases, even in the state of light traces, when they are brought to very low temperatures and to liberate thesegases at high temperatures. The lowest temperature always facilitates the most complete adsorption of traces of gas, while the regeneration temperature at which practically all the gases are liberated, is situated in the vicinity of 300 C. In certain application, such as for example compression of gases, it is arranged to cause thegasto be adsorbed by adsorbent elements from which it is then liberated in the hot state in a closed chamber, which is thusput under pressure. In other applications, for example in the case of vacuum pumps, it is on the contrary the adsorption operation which is of interest, and the heating of the adsorbent elements has no othereffect than to ensure their regeneration.

The disadvantage of known adsorbent elements is their period of action which, in the case of vacuum pumps, is longer than that of pumps of the diffusion type which are also employed in obtaining very high vacua. A certain reduction has recently been achieved in thisperiod of operation by improving the conditions of heat transfer to the adsorbent product, which possesses the property of a heat insulator. To this end, there was especially developed a composite adsorbent elementhaving a metallic support spread over the surface in the gards the speed and the degree of adsorption. Another object of the invention is a simple and rapid method of manufacture of such an adsorbent element. A third object of the invention is a device such as a pump, a compressor, a refrigerator, which incorporates adsorbent elements of this kind.

In the adsorbent element according to the invention, the material forming the support has good ductility characteristics, and the coating of adsorbent product is composed of dry particles agglomerated together by compression and partly incrusted in the said support of ductile material, so that the density of the said coating is substantially higher than the apparent density, before compression, of the powdered material which has been employed for the preparation of the said coating.

Experience has shown that theconsiderable increase in density of the coating permits either better performances to be obtained, that is to say a great effectiveness of adsorption as compared with a coating of the same thickness composed of the same particles, deposited and fixed by a binder, or results in a greater rapidity of adsorption as compared with a coating consisting of the same quantity, per unit surface area of the support, of adsorbent product fixed by a binder. This second improvement may be explained by the closer structure of the particles of adsorbent product permitting an easier transfer of heat, and also by the elimination'ofthe binder, although the invention provides, for the first of the reasons advanced above, an improvement in performance even with the use of adsorbent products to which is added an inert filler such as kaolin or alumina.

The method of manufacture of an adsorbent element of this kind is particularly characterized in that there is deposited on a support, preferably a sheet, of ductile material, a layer of particles of adsorbent product, an in that a mechanical pres- LII sure is applied on the said layer in order to convert it to a coating of particles agglomerated with each other and partly incrusted in the said support.

It is solely by the effect of mechanical pressure that the fixing is obtained by incrustation on the support of ductile material. There is preferably employed an elongated support in the form of a tape and the said tape is caused to pass, first of all into a powdering station which forms in a continuous manner a layer of particles of adsorbent product on one face or on both faces of the said tape, and then into a rolling station.

The thickness of the layer deposited in the powdering station must not be too large, otherwise the final coating will not be adequately fixed. There is no advantage in forming a layer having too small a thickness; the layer must'have a thickness amounting to several times the size of the particles of adsorbent product used. Thus, it appeared advisable not to exceed a thickness of the deposited layer of about 200 microns, where as a thickness less than 20 microns appears to be insufiicient to obtain suitable effectiveness.

However, these maximum and minimum thicknesses of the layer of deposited particles also depend on the granular size of the powder, and the figures indicated above apply to powders having a mean particle size comprised between 2 and 10 microns. When using powders having sizes comprised between 3 and 5 microns, there is effected the deposit of a layer having a thickness which does not exceed microns and which is greater than 30 microns.

Under these conditions, there is applied to the layer of powder thus deposited, a pressure which is as uniformly distributed as possible. The various tests which the Applicants have carried out by the use of an equipment which will be diagrammatically described below did not permit measurement in any simple manner of the pressure employed, but it was possible to take certain measurements which clearly illustrate the effect of this compression.

The structural effect particularly observed which resulted from the compression was an appreciable increase in density. In fact, the density of the deposited layer, which may be termed the apparent density of particles in the free state, and which is substantially that of the weight of the particles filling a volume of 1 cu. cm. was measured, during the course of these tests, as being of the order of 0.45 to 0.90 gram/cu.cm., where as the density of the final coating (to the exclusion of the metallic support) proved to be of the order of 1.45 grams/cucrn.

Now, this density approaches very close to the real density, of the order of 1.5 grams/cu.cm. of the same adsorbent product in the state of balls or beads of several millimeters in diameter. It may reasonably be concluded that the pressure employed was sufficiently high and that any higher pressure would not have resulted in any significant improvement.

Under these conditions, the thickness of the final coating is of the order of one-half to one-third of that of the deposited layer, and the utilization of pressures lower than those which were employed would necessarily lead to a smaller reduction in thickness between the deposited layer and the final coating, which would also reduce the performance and the quality of fixation of the final coating.

A final coating having a thickness of 20 to l00 microns proved suitable, but is was possible to establish that the optimum thickness was situated between 30 and 50 microns. In this latter case and with a threefold increase in the density-as defined abovethere was observed an excellent behavior of the coating employed. This behavior is not only excellent with respect to mechanical stresses, but also with respect to thermal stresses.

Thus for example, there was produced a composite adsorbent element consisting of a tape of pure aluminum on which there was formed, by the incrustation method described above, a coating of adsorbent product, the thickness of which was comprised between 30 and 50 microns. It was possible to form radii of curvature of 2 mm. in this coating, without any appreciable damage, and this sample was subjected, also without observing any deterioration, to a large number of rapid transitions from 200 to +300 C.

It was also possible to establish, all other things being equal and under operating conditions which necessitated a period of operation of several hours, and in a chamber in which the pressure was of the order of 10 5 torr and the temperature was 200 C., that the weight of gas adsorbed by a quantity of adsorbent product, forming the coating previously described, was to times greater than the weight of gas adsorbed by the same quantity of adsorbent product placed in a cartridge. This improvement is attributed to a smaller departure from thermo-dynamic equilibrium, due to improved pumping kinetics.

It has been stated above that it was possible to cause deformation of the coating of adsorbent product up to extremely small radii of curvature. Such deformations of the coating are of course only possible with supports which are themselves very thin, and the deformation tests given above were made on a coating of adsorbent product on an aluminum tape having a thickness of 50 microns. Such a support is particularly advantageous, on the one hand because it utilizes small quantities of relatively expensive metal, and because it permits deformation of the support enabling the composite adsorbent element to be produced with a small overall size.

An increase in the thickness of the support may result in better heat conduction from the thermal source, but this advantage does not generally counterbalance the disadvantages of a support which is too thick. A thick support is only of interest when it is desired to give the adsorbent element a selfsupporting characteristic which, for example, permits the construction of batteries of adsorbent elements in the form of a plate. On the other hand, the lower limit of the thickness of the support is determined in such manner that the particles in contact with this support are suitably incrusted, and it is therefore preferable to utilize a support having a thickness which is several times the mean size of the particles, and account should be taken of the reduction in thickness produced by creep during the application of theincrustation compression. In this way, it is possible to obtain an increase of 30 percent in the surface area of the support.

The material constituting the support must not only be ductile and malleable but it must also have good heat conductivity; the best adapted and least expensive metal is aluminum of high purity. In the tests which have been carried out by the applicants, the aluminum had a purity of 99.99 percent. The use of aluminum has a further advantage since its annealing temperature at 300 C. is precisely the regeneration temperature of the adsorbent products.

It is clear that by virtue of the method according to the invention, all binders may be eliminated, the compression alone being sufficient to ensure by incrustation a suitable and permanent fixation of the particles of adsorbent products in powder form. However, the use of a composite coating material, consisting of a mixture of powders of adsorbent products and one or more binders, such as kaolin or alumina, permits the thickness of the adsorbent to be increased and therefore finally the weight of adsorbent products per unit of surface area can be increased.

Experience has shown that there is an advantage in starting with adsorbent products which have been previously desiccated by regeneration at 300 C., followed by the adsorption of a dry gas, for example nitrogen.

Adsorbent elements of this kind have been proved by ex perience to be particularly effective, both with regard to the rapidity and the quality of operation, but on condition that they are in excellent thermal contact with the thermal source, which is of course a cold source when the elements are working as adsorbers. This is generally difficult to achieve, since the adsorbent products are themselves thermal insulators.

A further object of the present invention is to produce an adsorption device which comprises in a single construction unit a thermal source and a compartment of adsorbent elements of the type described above. It is also another object of the invention to produce such an adsorption device possessing an excellent thermal coupling between each of the adsorption elements and the thermal source. Still a further object of the invention consists of an arrangement of the adsorbent elements with respect to the thermal coupling means, such that interstices between the adsorbent elements are always left free so as to provide good accessibility to the gases, which is important in certain applications, such as vacuum pumping.

The invention starts from the condition that all the adsorbent elements of the kind referred to have a ductile metallic support, the very small thickness or edge of which is generally free from any coating of adsorbent product, and the invention is generally characterized in that the device comprises a storage compartment for adsorbent elements, separated in a gastight manner from a compartment incorporating a thermal source, and in that the elements of adsorbent product are fixed in the said storage compartment by a thermal coupling of at least a portion of the edge of each ductile support with a body which is a good conductor of heat in thermal contact with the thermal source.

It is by means of this thermal coupling with a part of the edge of the metallic supports of the adsorbent elements that it is possible to obtain rapid and very complete cooling of the adsorbent elements, whereby the effectiveness of the adsorbent elements is considerably increased. This thermal coupling may comprise either a weld between the edge of a support of an adsorbent element and the conducting body in thermal contact with the cold source, or a simple direct carrier member, preferably under pressure, of the edge of such an adsorbent element support against the conducting body in thermal contact with the thermal source.

Another object of the invention relates to a method of production of a thermal coupling by welding for an adsorbent device of the kind referred to above, and this method is especially characterized in that a bed of granular welding products is placed on the surface of a separation partition between the compartment incorporating the thermal source and the compartment incorporating the adsorbent products, in that discs of wound tape of adsorbent element are placed under pressure on the face covered with granular welded metal, and in that the whole is heated in acontrolled atmosphere to the melting temperature of the welding metal.

The characteristic features and advantages of the invention will be further brought out in the description which follows below, given by way of example, reference being made to the accompanying drawings, in which:

FIG. 1 is a view in cross section of an adsorbent element, FIG. la before compression and FIG. 1b after compression;

FIG. 2 is a diagrammatic form of construction of a machine for manufacturing these elements;

FIG. 3 is an alternative form of construction of a machine FIG. 2;

FIG. 4 is a view in cross section of an adsorbent ready to be used;

FIG. 5 is a view in transverse section of a first form of construction of an adsorption device according to the invention;

FIG. 6 is a view of the adsorption device of FIG. 5, in an intermediate stage of its manufacture;

FIG. 7 is a perspective view of a first alternative form of construction;

FIG. 8 is a diagrammatic view in axial section of the construction shown in FIG. 7;-

FIGS. 9 and 10 are views of two other alternative forms of construction of a device according to the invention;

FIG. 11 is an alternative form of the device shown in FIG. 10.

Referring first to FIG. la, there is deposited on each face of a support 1 of a thin sheet, for example aluminum, a layer 2 of particles of zeolites 3. The aluminum sheet may have a thickness of the order of microns, while the thickness of each layer deposited is of the order of I00 to 200 microns.

'The structure of the particles 2 is very aerated. After passing through a rolling mill, there is obtained the adsorbent element shown in FIG. 1b. By the effect of rolling, the sheet has crept and its thickness, shown at 1' is no more than 50 microns. What is remarkable however is that the layer of particles 3 has been converted to a coating 4 of these same particles incrusted in the aluminum sheet 1 and embedded one in the other, thus forming an agglomerated indeformable structure rigidly fixed on the support 1.

FIGS. 2 and 3 show a method of construction of an element such as described.

According to FIG. 2, two cylinders 20 and 21 m of very hard metal, similar to the cylinders of a rolling mill, rotate in opposite directions fl and f2, driving an aluminum tape 22 in the direction of the arrow f. Hoppers 23 and 24 deposit the powdered adsorbent product on the upper surfaces of the cylinders 20 and21, slightly on the downward side according to the direction of rotation. Due to their hardness, the cylinders 20 and 21 ensure the compression for the agglomerated and incrustation of the particles of powder only into the aluminum sheet.

'According to FIG. 3, an aluminum tape 30 passes into a fluidized bath of power of the adsorbent product 31 and then passes between the two rolling cylinders 32 and 33. It is possible to utilize an electrostatic powdering station, in which ionization electrodes are placed in the bath of fluidized powder, the casing of which is made of insulating material, while the aluminum tape is connected to earth. In this way, a uniform coating is obtained which is thicker and stable for a fairly long period, due to the electrical agglomeration of the power.

FIG. 4 shows a winding 40 consisting of a composite adsorbent element 41 wound on the tube 42 with the insertion along a generator line of intermediate tapes or wires 43 which are good conductors, of copper or aluminum, thermally connected to the cold source. The conductors serve at the same time as spacers, thus permitting the access of the gases to the whole volume of adsorbent product.

The adsorbent elements have performances of pumping kinetics remarkably superior to those of adsorbent products utilized in loose bulk, and have a substantial advantage both from the point of view of performance and production cost as compared with panels on which the adsorbent product is fixed by a binder.

With reference to FIGS. 5 and 6, it can be seen that a gasads orption device according to the invention comprises a chamber 51 with thermal insulation means 52, the said chamber being separated into two compartments 53 and 54 by a partition 55 of a metal which is a good conductor, for example of copper. The compartment 53 constitutes the thermal source and it is provided with a pipe 56 in the form of a coil, which served for the introduction of the cooling product associated with an electric heating resistance.

The compartment 54 incorporates an adsorbent element 57, the construction of which is briefly described below, and an opening 58 for coupling to a chamber to be pumped for example. This adsorbent element 57 is constituted by a winding in the form of a disc of tape of adsorbent product; which is in turn formed by a ductile metallic support strip 57a generally of aluminum of very small thickness, covered on both its faces with a coating layer 57b, 57c of adsorbent product consisting of dry particles incrusted by compression between each other and on the said ductile metallic support.

This disc 57 of wound tape is welded by its upper edge to the lower face of the separating partition 55, and the various welding points have been shown at 59. With reference to FIG. 6, it can be seen how this welding is carried out: The compartment 53 incorporating the thermal source is first formed, this compartment 53 being arranged at the welding station so that the welded face of the partition 55 is located above and horizontally. Over this face is spread a bed of granular welding metal, the disc or discs 57 of wound tape are arranged so that they rest on the bed of granular metal on their edges, and the disc is pressed against the partition 55 by means of a pressureplate 60 on which is placed a weight 61. The whole assembly is placed in a chamber under a controlled atmosphere, which may be either a high vacuum or a pure neutral gas, andthe whole is brought up to the melting temperature of the granular welding metal. This latter melts and it is only necessary to leave the assembly to cool, after which there is available a unit comprising the thermal source and the adsorbent product, this latter being connected to the thermal source by a plurality of welds 59 ensuring a very good thermal connection.

The choice of the welding product is important, since it must possess the following properties:

It must not necessitate any welding flux, the organic or polar vapors of which poison the adsorbent;

It must not contain metals which are too volatile, such as Hg, Cd, Ga, etc.,

It must melt at a temperature definitely below the melting temperature of aluminum namely 660, and also less than the degradation temperature of the zeolites (450/500C.);

It must wet aluminum and copper correctly, even in the absence of flux.

By way of example, two types of welding product have been adapted having the following composition by weight:

1. Germanium 53 percent-aluminum 45 percentmagnesium 2 percent; I

Melting temperatures 425 2. Aluminum between 40 and 63 percent-magnesium between 37 and 60 percent;

Melting temperature 460 The first has the advantage of melting at a lower temperature, whereas the second is a better wetting agent for the aluminum.

It will be observed that in this form of embodiment, the winding of the wound tape is sufficiently loose, so that the resulting geometry is sufficiently open for the molecules of gas passing into the chamber to be pumped to have easy access into the interstices provided in the tape.

Referring now to FIGS. 7 and 8, it can be seen that a ther mal source is essentially defined by a metallic bellows 81 of the tombac and two end walls 82 and 83 forming supporting plates between a plurality of discs or cakes of tape 85, 86, 87 and 88, and between each cake, intermediate supporting plates 89, 90, 91, of good conducting material, which are notched or perforated, for example in the form of a star, so as to permit the free passage of the gases from one cake to another. 7

In this form of construction, the intermediate plates 89, 90, 91 and the end-plates 82 and 93 are clamped, with the interposition of the cakes 88 by a tie rod 92 rigidly fixed to one extremity of the lower plate 82, and comprising a threaded portion on its free extremity on which is engaged a clamping nut 91. In this form of construction, both the end plates and the intermediate plates serve to form the thermal connection between the edges of the elements of adsorbent product and the thermal source.

According to the form of construction shown in FIG. 9, the geometry in this case is substantially close to that shown in FIG. 5, with this difference that a cake of wound tape is held under strong pressure against a separating wall 101, between a thermal source 102 and an adsorbent product compartment 103, by means of a kind of supporting spider 104 constituted by a plurality of arms 105 coupled to-each other by a threaded sleeve 106 and provided at their extremities with further threaded sleeves 107, all the central sleeves 106 and peripheral sleeves 107 being engaged on tie rods 108 of conducting material, rigidly fixed to the separating partition 101, and the spider is pressed against the cake of wound tape 100 by clamping screws 109, so as to form a double-conductive thermal connection, on the one hand between the upper edge of the cake 100 and the partition 101, and on the other hand between the lower edge of the cake 100, the tie rods 108 and this same partition 101.

In the arrangement shown in FIG. 10, the thermal contact is established by pairs of thermally conducting tie rods such as 110 and 111, which are welded at one extremity on the separating partition 112 between the compartment 113 of the thermal source and the compartment 114 of adsorbent product. On each pair of tie rods 110 and 111 are threaded stacks of rectangular plates 115 cutout from a tape of adsorbent product, and the thermal connection is in this case constituted by a connection between the tie rods 1 10 and 1 1 1 subjected to the action of pressure by nuts 116 and the edges of the perforations 117 of the plates 115.

In certain cases, conducting washers 118 are inserted between each plate 115 or between groups of plates 115 of adsorbent element, so as to cause a certain spreading out of these plates serving to provide better accessibility of the gaseous molecules between two superposed plates 115. Nuts 116 enable the locking of the plates 115 on each tie rod 110 and 111 and thus provide a better contact of the edges of the perforations 117 of the metallic support with the associated conducting tie rod 110 or 111.

The nature of the metal of the alloy of which the tie rods 110 and 111 are made is chosen in dependence on the results which it is desired to obtain. If it is desired to obtain a constant clamping effect, the tie rods are then made of a material having a coefficient of thermal expansion identical with that which forms the metallic support of the adsorbent elements. If on the contrary it is desired to ensure a very good thermal contact either at low or at high temperature, the tie rods are made of a material which contracts more than the materials forming the metallic support at high temperature or low temperature respectively.

For example, in order to obtain a good contact at low temperature, the tie rods may be made of copper, while the aluminum tape coated with zeolite contracts less than the copper, so that at 77 K., the pressure applied by the copper tie rods is very high and the thermal contact is very good. This arrangement is particularly useful for the manufacture of adsorption pumps cooled to 77 K. In other cases, in order to ensure a constant pressure, one or a number of elastic washers of bronze are interposed between the clamping bolt 116 and the plates of adsorbent tape. In this way, a constant pressure can be obtained irrespective of the temperature.

The results obtained by means of the arrangements described enable remarkable effectiveness of the adsorbent product to be achieved. For example, with an arrangement of the kind described in FIG. 10, it has been possible to apply cold to a structure of adsorbent product containing 500 grams of zeolite deposited on an aluminum tape of mm. in width, the copper tie rods being spaced apart by 50 mm. and having a diameter of 10 mm., the period of cooling of the unit from 450 to 77 K. being 15 minutes.

In accordance with FIG. 11, the cutout plates 120 are in this case fixed so as to present their lower edges facing the communication passage 121 with the chamber to be exhausted. Between the plates 120 are placed washers 22 which form spacers. This arrangement is especially advantageous in obtaining very high vacua, the accessibility of the gaseous molecules to the adsorbent being optimum.

What we claim is:

1. A composite gas-adsorbing element comprising a flat tapelike support of ductile metallic material and, on at least one face of said flat support, a coating of gas-adsorbing products such as zeolites, said coating being constituted by dry solid particles directly agglomerated together and partly incrusted by compression in said support of ductile material, the density of said coating being substantially greater than the apparent density, before compression, of this same powdered material in the state of a mass of free particles and the thickness of said coating being from 10 to 100 microns.

2. A gas-adsorbing element as claimed in claim 1, in which the material forming said ductile support is a member selected from the group consisting of gold, silver, copper and aluminum.

3. A gas-adsorbing element as claimed in claim 1, in which the density of said coating is at least twice as great as the apparent density of this same material in the state of a mass of free particles.

4. A gas-adsorbing element as claimed in claim I, in which the size of the particles of said coating is 2 to 10 microns.

5. A gas-adsorbing element as claimed in claim 1, in which the thickness of said coating is from 30 to 50 microns.

6. A gas-adsorbing element as claimed in claim 1, in which said support of ductile material is a sheet having a thickness of 20 to microns.

7. A method of manufacture of a composite gas-adsorbent element, said method comprising the steps of: electrically charging a flexible tape of ductile metallic material, passing said tape into a fluidized bath of zeolite particles to effect a continuous deposit of a layer of said particles on both faces of said tape, and pressure rolling said tape to convert said layer to an adherent coating of particles agglomerated together and partly incrusted in said tape.

8. A method of manufacture of an adsorbent element as claimed in claim 7, in which the thickness of the layer of solid particles deposited on said tape is from 20 to 200 microns, the pressure applied converting said layer into a coating of particles agglomerated together and incrusted in said tape, said coating having a thickness of 10 to 100 microns.

9. A gas-adsorbing element as claimed in claim 1, and further comprising thermally conductive means in thermal contact with said tape.

10. A gas-adsorbing element comprising a flat flexible tapelike support of ductile metallic material and, on at least one face of said flat support, a coating of gas-adsorbing products such as zeolites, in the form of solid particles directly agglomerated with each other and partly incrusted in said support, said support being wound radially on itself in a coil, and spacer means'of thermally conductive material extending at intervals along the transverse direction of said flat elongated support.

11. A gas-adsorbing device comprising a first compartment, means for bringing thermal energy into said first compartment, a second compartment, in said second compartment at least one gas-adsorbing element comprising a flat flexible tapelike support of ductile metallic material, and on at least one face of said flat support, a coating of gas-adsorbing products such as zeolites, said coating being in the form of solid particles directly agglomerated together and partly incrusted in said support, and thermal connection means between the metallic support of each gas-adsorbing element and said first compartment.

12. A gas-adsorbing device as claimed in claim 11, in which said thermal connection means comprise a conducting body and a plurality of welding points between said conducting body and the metallic support of each said adsorbent element.

13. A gas-adsorbing device as claimed in claim 11, in which said thermal connection means comprise a conducting body with an extended surface and direct contact means of the edge of the support of said adsorbent element against said conducting body.

14. A gas-adsorbing device as claimed in claim 13, in which said direct contact means comprise pressure means for applying continuous mechanical pressure.

15. A gas-adsorbing device as claimed in claim 11, in which the ductile metallic support of each adsorbent element is wound radially on itself to form a coil, said thermal connection means comprising a flat conducting body and means for ensuring direct thermal contact between one edge of each said metallic support and said flat conducting body.

16. A gas-adsorbing device as claimed in claim 11, comprising a plurality of adsorbent elements formed by a stack of plates with perforations, said thermal connection means comprising tie rods passed through the perforations of said plates, said tie rods being in thermal contact with the metallic supports of said adsorbent plates at the point of said perforations.

17. A gas-adsorbing device as claimed in claim 15, in which -a plurality of said adsorbent coils are superimposed on each other and in whichsaid thermal connection means comprise port of an adsorbent element incorporate intermediate parts in thermal contact with said thermally conductive separating partition between said first and second compartments.

20. A gas-adsorbing device as claimed in claim 19, in which said separating partition is of the cylindrical bellows type, said second compartment being external to and surrounding said first compartment.

21. A gas-adsorbing device as claimed in claim 20, in which said thermal connection means comprise an axial tie rod and at least two end-plates adapted to clamp between them the coils of wound tape, said tie rods tending to pull together said end-plates.

22. A gas-adsorbing device as claimed in claim 12, in which the welding material employed for each said welding point has a melting point comprised between 300 and 400, and has an affinity for aluminum.

23. A method of preparation of a thermal connection by welding for an adsorbent device as claimed in claim 12, in which a bed of granular welding material is placed on the surface of said separating partition between the first and second compartments and in which the coils of wound tape are applied under pressure against the face covered with said granular welding material, and in which the whole assembly is heated in a controlled atmosphere to the melting temperature of said granular welding material.

24. A gas-adsorbing device as claimed in claim 16, in which each said tie rod is made of a material having a coefficient of expansion identical with or different from that which constitutes the metallic support of said adsorbent elements, depending on the pressure effect which it is desired to obtain in operation. 

2. A gas-adsorbing element as claimed in claim 1, in which the material forming said ductile support is a member selected from the group consisting of gold, silver, copper and aluminum.
 3. A gas-adsorbing element as claimed in claim 1, in which the density of said coating is at least twice as great as the apparent density of this same material in the state of a mass of free particles.
 4. A gas-adsorbing element as claimed in claim 1, in which the size of the particles of said coating is 2 to 10 microns.
 5. A gas-adsorbing element as claimed in claim 1, in which the thickness of said coating is from 30 to 50 microns.
 6. A gas-adsorbing element as claimed in claim 1, in which said support of ductile material is a sheet having a thickness of 20 to 100 microns.
 7. A method of manufacture of a composite gas-adsorbent element, said method comprising the steps of: electrically charging a flexible tape of ductile metallic material, passing said tape into a fluidized bath of zeolite particles to effect a continuous deposit of a layer of said particles on both faces of said tape, and pressure rolling said tape to convert said layer to an adherent coating of particles agglomerated together and partly incrusted in said tape.
 8. A method of manufacture of an adsorbent element as claimed in claim 7, in which the thickness of the layer of solid particles deposited on said tape is from 20 to 200 miCrons, the pressure applied converting said layer into a coating of particles agglomerated together and incrusted in said tape, said coating having a thickness of 10 to 100 microns.
 9. A gas-adsorbing element as claimed in claim 1, and further comprising thermally conductive means in thermal contact with said tape.
 10. A gas-adsorbing element comprising a flat flexible tapelike support of ductile metallic material and, on at least one face of said flat support, a coating of gas-adsorbing products such as zeolites, in the form of solid particles directly agglomerated with each other and partly incrusted in said support, said support being wound radially on itself in a coil, and spacer means of thermally conductive material extending at intervals along the transverse direction of said flat elongated support.
 11. A gas-adsorbing device comprising a first compartment, means for bringing thermal energy into said first compartment, a second compartment, in said second compartment at least one gas-adsorbing element comprising a flat flexible tapelike support of ductile metallic material, and on at least one face of said flat support, a coating of gas-adsorbing products such as zeolites, said coating being in the form of solid particles directly agglomerated together and partly incrusted in said support, and thermal connection means between the metallic support of each gas-adsorbing element and said first compartment.
 12. A gas-adsorbing device as claimed in claim 11, in which said thermal connection means comprise a conducting body and a plurality of welding points between said conducting body and the metallic support of each said adsorbent element.
 13. A gas-adsorbing device as claimed in claim 11, in which said thermal connection means comprise a conducting body with an extended surface and direct contact means of the edge of the support of said adsorbent element against said conducting body.
 14. A gas-adsorbing device as claimed in claim 13, in which said direct contact means comprise pressure means for applying continuous mechanical pressure.
 15. A gas-adsorbing device as claimed in claim 11, in which the ductile metallic support of each adsorbent element is wound radially on itself to form a coil, said thermal connection means comprising a flat conducting body and means for ensuring direct thermal contact between one edge of each said metallic support and said flat conducting body.
 16. A gas-adsorbing device as claimed in claim 11, comprising a plurality of adsorbent elements formed by a stack of plates with perforations, said thermal connection means comprising tie rods passed through the perforations of said plates, said tie rods being in thermal contact with the metallic supports of said adsorbent plates at the point of said perforations.
 17. A gas-adsorbing device as claimed in claim 15, in which a plurality of said adsorbent coils are superimposed on each other and in which said thermal connection means comprise flat intermediate conducting supports between the edges of two adjacent coils, said intermediate supporting bodies being permeable to gases and being made of thermally conductive material.
 18. A gas-adsorbing device as claimed in claim 17, in which said thermal connection means comprise a separating partition, of thermally conductive material, between said first and second compartments.
 19. A gas-adsorbing device as claimed in claim 18, in which said thermal connection means between the edge of the support of an adsorbent element incorporate intermediate parts in thermal contact with said thermally conductive separating partition between said first and second compartments.
 20. A gas-adsorbing device as claimed in claim 19, in which said separating partition is of the cylindrical bellows type, said second compartment being external to and surrounding said first compartment.
 21. A gas-adsorbing device as claimed in claim 20, in which said thermal connection means comprise an axial tie rod and at least two end-plates adapted to clamp between them the coils of wound tape, said tie rods tending to pull together said end-plates.
 22. A gas-adsorbing device as claimed in claim 12, in which the welding material employed for each said welding point has a melting point comprised between 300* and 400*, and has an affinity for aluminum.
 23. A method of preparation of a thermal connection by welding for an adsorbent device as claimed in claim 12, in which a bed of granular welding material is placed on the surface of said separating partition between the first and second compartments and in which the coils of wound tape are applied under pressure against the face covered with said granular welding material, and in which the whole assembly is heated in a controlled atmosphere to the melting temperature of said granular welding material.
 24. A gas-adsorbing device as claimed in claim 16, in which each said tie rod is made of a material having a coefficient of expansion identical with or different from that which constitutes the metallic support of said adsorbent elements, depending on the pressure effect which it is desired to obtain in operation. 